Settlement reduction analysis on soft soil in Demak-Kudus National Highway with stone column

The North Coast of Java Highways, especially the Demak-Kudus Section is dominated byalluvium where soft soil is commonly found. This fact is supported by SPT and boring test results that show soft soil deposits exist in 0-18 m depth of testing points. The soft soil existence is causing settlement and resulting in damage to the existing highway. In this case, it is not possible to dismantle the road embankment and then soil improvement using a stone column is proposed to densify and reduce the settlement of the soil.Based on analysis results, settlements without soil improvement in BH-1 and BH-2 are 0.0424 m and 0.3277 m respectively. Furthermore, the reduction of settlements analysis using the Priebe and Equibrillium method shows that a stone column with a 1 m diameter can satisfy requirements of settlement < 0.1 m if the spaces are 1.5 m and 2.5 m respectively for triangle arrangement. Settlement after improvement theoretically according to the Priebe and equibrillium methods are 0.0717 m and 0.098 m respectively.